1. Field of the Invention
The present invention relates to silver halide black and white or color photographic materials and, more particularly, the present invention relates to silver halide color photographic materials wherein the undesirable influence of ultraviolet light are eliminated by the incorporation of specific ultraviolet absorbing agents into the silver halide photographic materials.
2. Description of the Prior Art
It is quite well known that ultraviolet light is harmful to photographic materials in many respects. Generally speaking, a photographic material, comprising a support of relatively high electric insulation such as films of cellulose triacetate, poly(ethylene terephthalate), polystyrene or polycarbonate, and paper laminates covered by such films and a light sensitive, photographic emulsion coating mainly comprising silver halide provided on the support, has surfaces of a fairly high electric insulative nature. Hence, during the manufacture and handling of the photographic material, the surfaces tend to be electrostatically charged through contact and friction with or separation from a foreign material of the same or different compositions. When the generated electrical charge accumulates to a certain critical level, the electrical charge discharges into the air forming discharging sparks. A photographic material, which has been subjected to such discharging sparks, has various irregular discharge patterns, such as arborescent, feather-like, spotty or radial patterns, thereon after development. These undesirable patterns occurring due to the above-described reason are referred to, in general, as static marks in the photographic art.
It is also well known in the photographic art that the spark light responsible for static marks is spectrally distributed between wavelengths of about 200 and about 550 nm, and that light between wavelengths of about 300 and about 400 nm is most abundant energetically. Therefore, as described in, for example, Japanese Patent Publication No. 10726/1975, Japanese Patent Application (OPI) No. 26,021 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), French Pat. No. 2,036,679, etc., various attempts have been made to reduce the generating frequency of static marks by using a UV absorbing agent which effectively absorbs light between about 300 and about 400 nm to prevent the UV light from reaching the photo-sensitive layer.
Separately, except for lith-films and X-ray films which are used with specific light sources, general purpose photographic materials are also adversely affected by UV light present in the light used for image exposure. For example, monochromatic photographic materials tend to produce disadvantageously low contrast images when exposed to objects reflecting a large amount of UV light such as snow-covered landscapes, seashores or the sky. Color photographic materials, which are expected to record visible light only, suffer from the effects of UV light. As an example, objects such as distant landscapes, snow scenes, asphalt-paved roads, etc. which are abundant with UV region light tend to assume a cyan appearance. In addition, the color reproduction characteristics of photographic pictures obtained by the use of various light sources (sunlight, incandescent lamps and fluorescent lamps) depend to a great extent on the kind of light source used. One reason of this dependence is the difference in the spectral energy in the UV region present in the light. An exposure with an incandescent lamp causes the color image to be more reddish than that with sunlight, while an exposure with a fluorescent lamp will cause the color image to have a more bluish tint than that with sunlight. Accordingly, in order to achieve a correct color reproduction, prevention of UV light from reaching the silver halide photo-sensitive layers in the photographic film is quite effective. Various descriptions of this approach appear in, for example, Japanese Patent Publication No. 49029/1977 and U.S. Pat. No. 4,045,229, etc.
Moreover, color pictures, particularly those comprising dyes resulting from color development, are susceptible to UV light, which causes the dye image to fade and a discoloration thereof. On the other hand, the dye precursers remaining in the emulsion coating after color development produce a color stain when subjected to the action of UV light. Such a color stain is self-evidently undesirable for the finished product print. Of the variety of color photographic products available, reflection-type, positive prints are most likely to be subjected to UV radiation, since they are frequently observed under an intense illumination of sunlight which contains a large amount of UV light. The fading and discoloration of dye images are particularly promoted by light with wavelengths between about 300 and about 400 nm. In order to reduce the effect of the UV light in this wavelength region, various UV absorbing agents have been developed including those described in, for example, U.S. Pat. Nos. 3,215,530, 3,707,375, 3,705,805, 3,352,681, 3,278,448, 3,253,921, 3,738,837 and 4,045,229, Japanese Pat. Publication Nos. 26138/1974 and 25337/1975, and British Pat. No. 1,338,265. U.S. patent application Ser. No. 896,870 filed Apr. 17, 1978 discloses photographic materials containing novel UV absorbing agents.
UV absorbing agents for photographic products used to eliminate the various harmful effects of UV light described above should preferably have the following characteristics:
(1) complete or substantial transparency to visible light PA1 (2) Good compatibility with the binder material PA1 (3) Inertness to the photographic additives present in the silver halide light-sensitive member as well as in the photographic processing solutions. PA1 (4) High efficiency of UV light absorption, particularly in the wavelength region between about 300 and about 400 nm. PA1 (5) High stability to the action of UV light, heat and humidity
Most conventional UV absorbing agents employed in silver halide photographic material not only do not meet these requirements, but also were not suited for the present purposes. For example, benzotriazole derivatives set forth in U.S. Pat. No. 3,253,921 and cinnamic acid derivatives set forth in U.S. Pat. Nos. 3,707,375 and 3,705,805, both of which have been extensively employed in photographic materials, have poor absorption characteristics in the spectral region between about 300 and about 400 nm, particularly between 365 and 400 nm with a broad tail near 400 nm.
Accordingly, such a UV absorber needs to be incorporated in a relatively high concentration in order to ensure the necessary absorbance, in which case, however, a considerable fraction of blue light with wavelengths longer than 415 nm is also absorbed, resulting in a decrease in the photographic speed and an undesirable coloration (stain). Therefore, the amount in the photographic material must be suppressed, and thus effective absorption of the UV light of wavelengths between about 365 and about 400 nm is not achieved, and satisfactory improvements in static mark prevention, color reproduction chcaracteristics and light fastness of the dye images are not obtained. Incorporation of a UV absorber in an amount sufficiently high to effectively achieve such improvements often results in additional technical problems including, for example, a poor adhesion between different coatings superimposed to form a multi-layer photographic material, and a deterioration in the physical properties of the film as represented by an increased tendency toward surface blocking, etc.